Controlling hardness of anchor bolt expansion sleeves

Abstract

A masonry anchor including a sleeve having one or more protuberances extruded from its sidewall, said sleeve being annealed to a hardness not to exceed a Brinell hardness number of 230 so as to allow said protuberances to deform into a flattened state to increase the overall holding power of said anchor.

I claim: 
     
       1. An anchor for use in a pre-drilled hole in masonry or the like, said anchor including a sleeve structure of a work hardenable material having a Brinell hardness number in the range of 100 to 230 expandable into contract with the side of said hole, said sleeve including one or more extruded external protuberances adapted to initially engage the sidewall of said hole, said sleeve being annealed from an initial hardness exceeding a 230 Brinell hardness number to said Brinell hardness number in the range of 100 to 230 to reduce the effect of work hardening occasioned by the fabrication process, thereby allowing flattening of said protruberances and facilitating full area engagement of said sleeve with the side of said hole whereby formation of localized areas of stress concentration is prevented. 
     
     
       2. A method of forming a sleeve suitable for use in an anchor bolt assembly comprising the steps of forming said sleeve into the desired configuration including one or more embossed protruberances formed integral with said sleeve, said sleeve being formed of a work hardenable material having a hardness after fabrication exceeding a 230 Brinell hardness number; and heat treating said sleeve to reduce the effect of work hardening occasioned by the fabrication process, to a hardness within the range of 100-230 Brinell hardness number which will allow said protruberances to flatten when the sleeve is expanded into engagement with the sidewall of a hole to allow maximum area contact of the sleeve with the opening and eliminate localized stress points normally caused by said protruberances.